In a non-stick pot, whisk together your eggs, egg yolks, and brown sugar until combined. Heat over medium and continue to whisk until the sugar has dissolved, then add in the pumpkin, half and half, vanilla, and spices. Whisk to combine, then bring to a simmer. Whisk continuously for the next 8 minutes or so, until quite thickened, then remove from the heat and add in your butter, one cube at at time, until fully combined. Press the custard through a mesh sieve, place in a bowl, and cover with plastic wrap, being sure to press the plastic to the custard so that it does not form a skin. Refrigerate for a minimum of 6 hours, but preferably, overnight.

Preheat your oven to 350 degrees F. Whisk together the flour, cocoa powder, baking soda, and salt in a small bowl and set aside. In the bowl of your mixer, beat together the butter and sugar until light and fluffy, about 3 minutes, then add in the egg, beat until combined, followed by the vanilla.

Add in the flour and milk in alternating intervals, starting and ending with the flour. Beat until just moistened and scrape down the sides of the bowl as necessary. Line your baking sheets with parchment and scoop out 2 to 3 teaspoon sized balls of dough and place on the sheets. Leave about 2 inches of space between each one, as it will spread out just a bit. Bake for 12 minutes or so, until set. Allow to cool completely before sandwiching with the custard. The finished whoopie pies may be stored in an airtight container in the refrigerator for up to 2 days.

Recipe by The Crepes of Wrath at http://www.thecrepesofwrath.com/2012/10/31/chocolate-whoopie-pies-with-pumpkin-custard-filling/